Theft of portable equipment such as personal computers and other office equipment is widespread and imposes significant costs on individuals and businesses. Developing a common security solution to prevent theft of portable equipment has proven challenging, because portable equipment varies so much in terms of size, shape and construction. Accordingly, previous attempts to provide a common, inexpensive and secure method to protect even a single class of portable equipment, such as personal computers, have been largely unsuccessful.
One particular type of security device for portable equipment uses interlocking plates to affix the underside of an office equipment unit to a work surface. U.S. Pat. No. 4,655,429 to Gaensle et al. (1987) discloses fixture with plates and a bonding method to secure them. Other methods have the user drill holes in the work surface to bolt the interlocking plates together from underneath.
These methods are satisfactory for certain applications, but are generally unacceptable because they make movement of the equipment time consuming and difficult when offices are relocated, sometimes forcing permanent modifications to be made to the equipment or anchoring surface, and do not allow the user the option of repositioning the equipment once it has been installed. In addition, many of these devices must be manufactured to fit the specific geometry of the machines they secure, making them expensive to manufacture and purchase.
Another class of devices that share many of these same drawbacks encase the equipment to be protected in a protective housing using various methods to anchor the housing to a secure location. Several types of these devices have been disclosed. For example, U.S. Pat. No. 4,123,922 to Kuenstler (1978) describes various means to lock equipment inside a protective housing. U.S. Pat. No. 4,252,007 to Kerley (1981) discloses a protective housing of similar intent but different design. Although appropriate for certain applications, these devices must be designed to house a particular size and shape of equipment, making them expensive to manufacture and purchase. In addition, they have the drawback of dramatically altering the appearance of the office equipment.
To overcome these objections consumers have resorted to security devices that have more flexible anchoring methods. Many of these devices utilize steel cable, sometimes referred to as "wire rope", to tether personal computers and other office equipment in place. Some steel cable devices use existing screws to secure the cable to the office equipment. First, a bracket is mounted to the equipment using an existing screw. Then the steel cable is passed through the bracket, blocking removal of the screw. These devices can be used on a broad variety of computers, are inexpensive to manufacture and can be removed when no longer desired. However, these screw attached devices have some disadvantages. First, the security provided by this method is based on the strength of the screw arrangement which anchors the bracket. Most personal computers have relatively small, frail screws. Additionally, the surfaces that they screw into are generally thin and easily stripped by wrenching forces on the cable and screw. Consequently, a thief, depending on the personal computer, could dislodge the bracket with a good quick tug. Another disadvantage is the difficulty that users encounter mounting these devices. Many users have a difficult time visualizing how these devices are utilized and installed.
Another steel cable device uses a tether to anchor a housing that encases the equipment. This approach has the same drawbacks as the other protective housing approaches mentioned above. They are expensive and dramatically alter the appearance of the equipment they are protecting.
Still other office equipment steel cable devices, as disclosed in U.S. Pat. No. 3,785,183 to Sander (1974), U.S. Pat. No. 3,859,826 to Singer et. al. (1975), U.S. Pat. No. 3,990,292 to Shontz (1992) and U.S. Pat. No. 4,310,371, to Herwick et. al. (1981), focus on elaborate keylock assemblies. These devices are expensive and fail to provide a simple and widely applicable method to attach the steel cable to a personal computer or other office equipment. For attaching the cable to equipment to be secured, Sanders suggests making a hole in the equipment to take advantage of the disclosed lock and back plate assemblies. Most users find this unacceptable because they do not wish to drill into the equipment for fear of violating the warranty or damaging the equipment. Singer et. al. suggests using tamper proof screws to attach to the equipment to take advantage of the disclosed locking assembly. This assumes that there are suitable screw mounting sites that are in the necessary location to mate with the particular security plate for the equipment. Additionally, security screws are only suitable as long as a thief does not have the correct screwdriver. Shontz suggests drilling a hole in the office equipment, finding a suitably located and sized hole, or adapting a plate to fit existing nuts and bolts to mount the cable. This approach has many of the same disadvantages that are apparent in the Sander disclosure.
A more satisfactory means for securing portable equipment has been developed which takes advantage of existing plates or fittings on the equipment to provide anchoring attachments for security fittings. Such security devices replace the plate or fitting with a security fixture which is designed to be securely mounted in the original location of the plate or fitting. Ideally, such devices are mounted without exposed screws or bolts which may be removed by unauthorized persons. One such security device specifically designed for personal computers is a mechanical security fixture which mounts to a standard expansion slot opening in the personal computer chassis. This security fixture can be used on a broad range of personal computers, can be securely mounted without exposed screws or bolts, and takes advantage of the integrity of the computer chassis to provide a strong mounting location for the security fixture.
A recent development in the field of security devices for portable equipment has been the use of security fixtures which are specifically designed to mate with standardized openings manufactured into the chassis of the equipment. One such chassis mating fixture commonly used in personal computers and other portable office equipment is a lockable mating fixture manufactured by Kensington, Inc., San Mateo, Calif., adapted to mate with standardized, oval shaped security slots manufactured into the chassis of the equipment. Such security slots are now routinely provided for a range of portable computers, such as laptop and notebook computers sold under the Macintosh.RTM. trademark (Apple Computers, Inc., Cupertino, Calif.), as well as manufactured by Dell.RTM. (Austin, Tex.), AST.RTM. (Irvine, Calif.), and Toshiba USA.RTM. (Irvine, Calif.), among others. The slots are designed to lockably engage a t-shaped head connected by a rotatable shaft to the security fixture which is in turn anchored to a stationary object by an anchoring tether.
To attach the Kensington fixture to the portable equipment, the head is inserted into the slot through the wall of the chassis of the equipment and the shaft is then rotated by insertion and rotation of a key into the device. This rotates the head out of line with a longitudinal axis of the slot into an engaged position, so that removal of the head is blocked by an interior wall of the chassis surrounding the slot. Removal of the head can then only be accomplished if the head is further rotated or counter-rotated to realign the head with the longitudinal axis of the slot.
To prevent counter-rotation and removal of the head once it is engaged, the Kensington device provides an elaborate head locking system. The system includes a head locking mechanism consisting of two pins mounted on either side of the shaft in line with an insertion plane defined by the head and shaft when the head is in the non-engaged position. The length of a horizontal, slot-mating portion of the head, and the spacing between the locking pins, approximates the length of the slot so as to enable simultaneous insertion of the head and pins into the slot. once the head and pins are inserted into the slot, the shaft and head are rotated about the shaft axis, while the pins remain stationary in the slot. Once the key is removed, the head becomes locked in the engaged position and cannot be independently angularly rotated about the longitudinal axis of the shaft relative to the pins, which themselves cannot be angularly rotated with respect to the shaft axis because such action is blocked by sidewalls of the slot.
While the Kensington device features a number of advantages over alternative security devices for portable equipment, it also features a number of disadvantages. Primary among these disadvantages is the complex head locking system which imposes extensive manufacturing costs. In addition, use of the Kensington device is limited to portable equipment manufactured to include a security slot opening in the chassis, making the device incompatible with a wide range of portable equipment.
Accordingly, a need exists in the art for a security fixture for securing portable equipment having a security slot opening in the chassis of the equipment, which is simple in design and inexpensive to manufacture. In addition, there is a need in the art for a means of adapting portable equipment which has not been manufactured to include a slot opening to make such equipment securable by slot-mating security fixtures.